Analysis of Label Breakage Issues in Automatic Labeling: Four Types of Causes and Identification Characteristics

Label breakage during automatic labeling is a common fault that affects production efficiency. It not only causes downtime but may also damage equipment components. To accurately identify the root cause, the first step is to examine the fracture pattern of the backing paper. The following are four typical causes and their corresponding characteristics:

I. Backing Paper Edge Damage – Caused by Transportation or Roller Pressure

After die-cutting, labels typically retain a backing paper margin wider than the label itself to facilitate handling and positioning during application. During packaging, transport, and transfer, this marginal area is prone to minor cracks if subjected to squeezing or impact. During automatic labeling, the tension generated by the equipment may propagate along these cracks, causing the backing paper to tear from the edge. In addition, improperly adjusted guide rollers or pressure rollers on the labeling machine may directly compress the backing paper edge, resulting in regular indentations and ruptures. The characteristic feature of this type of breakage is that the cracks extend neatly along the backing paper edge with a relatively regular appearance.

II. Adhesive Seepage Causing Internal Adhesion – Induced by High Temperature or Excessive Rewind Tension

When label rolls are rewound too tightly or stored in high-temperature environments, the adhesive layer may be squeezed out and adhere to the back of the backing paper, creating interlayer bonding. Under such conditions, the label roll encounters additional resistance during unwinding, and the equipment must overcome internal adhesive forces during tensioning. If the backing paper is relatively narrow with limited tensile strength, it is highly susceptible to breakage under the combined effect of applied tension and internal resistance. This type of breakage is characterized by a relatively flat but irregular fracture surface, with no visible mechanical scratches or pre-existing cracks.

III. Improper Die-Cutting Parameters – Excessive Pressure Damaging the Backing Paper

Die-cutting is a critical process affecting label separation quality. If the die-cutting pressure is set too high, the blade may penetrate through the face material and damage the backing paper fibers, reducing its tensile strength. During subsequent automatic labeling, once tension is applied, the backing paper is prone to fracture along the die-cut line. In such cases, the cracks typically extend along the die-cutting direction, with neat cross-sections and clear cutting marks, noticeably different from fractures caused by normal tension or wear.

IV. Release Coating Damage – Coating Defects or Accidental Scratching

If the release coating (usually silicone) on the backing paper surface is scratched or unevenly applied during raw material production or printing, localized release-force variations may occur. During labeling, the altered resistance at damaged areas can easily cause the backing paper to tear. Additionally, improper handling during quality inspection, re-labeling, or transport in printing facilities may also cause accidental scratching of the coating. This type of breakage is characterized by jagged, irregular fracture edges, with cracks that do not repeat at the same positions, requiring further inspection of the coating surface for confirmation.